Does anyone know how to do geometry

So all the angles on one side should equal 180.
50+55= 105
180-105=75
12x+3=75
12x=72
12*6=72
x=6

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!